Two-wheeled Motorcycle F-ACT EVO
User’s Instruction and Maintenance Manual
KEEWAY Motorcycle Co., Ltd
- 1 -
Content ................................................................. 错误！未定义书签。
Preface .............................................................................. - 3 -
Preparation Data ................................................................. - 4 -
Inspection/Adjustment ........................................................... - 36 -
Inspection and maintenance of electrical system ..................................... - 50 -
1. Battery/charging system .......................................................... - 52 -
1.1 Preparing documents ......................................................... - 52 -
1.2 Failure diagnosis ........................................................... - 53 -
1.3 Battery ..................................................................... - 54 -
1.4 Charging System ............................................................. - 55 -
1.5 Rectifier ................................................................... - 56 -
1.6 Magnetor Charging Coil ...................................................... - 56 -
1.7 Magnetor Lighting Coil ...................................................... - 57 -
2. Ignition System .................................................................. - 60 -
2.1 Material Preparation ........................................................ - 60 -
2.2 Failure Diagnosis ........................................................... - 61 -
2.3 Ignition System Inspection .................................................. - 62 -
2.4 CDI Group ................................................................... - 64 -
2.5 Ignition Coil ............................................................... - 64 -
2.6 Trigger ..................................................................... - 65 -
3. Activation System ................................................................ - 67 -
3.1 Material Preparation ........................................................ - 67 -
3.2 Failure Diagnosis ........................................................... - 68 -
3.3 Starting Motor .............................................................. - 68 -
3.4 Starting Relay .............................................................. - 70 -
4. Bulbs/Switches/Meters ............................................................ - 73 -
4.1 Material Preparation ........................................................ - 73 -
4.2 Failure Diagnosis ........................................................... - 73 -
4.3 Headlight Bulb Replacement .................................................. - 73 -
4.4 Front Turn Signal Lamp Bulb Replacement ..................................... - 74 -
4.5 Taillight Bulb Replacement .................................................. - 74 -
4.6 Meters ...................................................................... - 75 -
4.7 Power Lock .................................................................. - 75 -
4.8 Speaker .......................................................................... 76
4.9 Handle switch ..................................................................... 76
The check and maintenance of the chassis ...................................................... 77
5. Brake ................................................................................. 80
5.1 Maintenance instructions ............................................................. 80
5.3 Front hydraulic brake ............................................................ - 82 -
5.4 Rear hub brake ................................................................. - 83 -
6. Body cover ......................................................................... - 87 -
7. Front wheel/front suspension ........................................................... - 92 -
7.1 Preparation data ................................................................ - 92 -
7.2 Fault diagnosis ................................................................. - 92 -
- 2 -
7.3 Front wheel ................................................................... - 93 -
7.4 Direction handle................................................................ - 96 -
7.5 Front fork ..................................................................... - 96 -
8. Rear wheel/rear suspension ........................................................... - 100 -
8.1 Preparation data ............................................................... - 100 -
8.2 Fault diagnosis ................................................................ - 100 -
8.3 The rear wheel ............................................................. - 101 -
8.4 Rear muffler .................................................................. - 102 -
9. Tank/seat cushion ................................................................... - 106 -
9.1 Preparation data ............................................................... - 106 -
9.2 Fault diagnosis ................................................................ - 106 -
9.3 Tank/seat cushion .............................................................. - 107 -
Check and maintenance of the engine ..................................................... - 108 -
10. Lubricating system................................................................. - 111 -
10.1 Preparation data .............................................................. - 111 -
10.2 Fault diagnosis ............................................................... - 111 -
10.3 Machine oil pump ............................................................ - 112 -
11.1 Preparation data .............................................................. - 115 -
Operation precautions ............................................................. - 115 -
11.2 Fault diagnosis ............................................................... - 115 -
11.3 Disassembly of carburetor ...................................................... - 116 -
11.4 Assembly and adjustment ...................................................... - 118 -
12. Cylinder cover .................................................................... - 121 -
12.1 Preparation materials .......................................................... - 121 -
12.2 Failure diagnosis ............................................................. - 121 -
12.3 Cylinder cover ............................................................... - 121 -
12.4 Checking of cylinder cover ..................................................... - 122 -
12.5 Assembly of cylinder cover ..................................................... - 122 -
Thirteenth, Cylinder block and piston ..................................................... - 124 -
13.1 Preparation materials .......................................................... - 124 -
13.2 Failure diagnosis ............................................................. - 125 -
13.3 Cylinder block ............................................................... - 125 -
13.4 Piston ...................................................................... - 126 -
13.5 Assembly of piston ........................................................... - 128 -
14.1 Preparation of materials ........................................................ - 131 -
14.2 Failure diagnosis ............................................................. - 131 -
14.3 Left crankcase cover .......................................................... - 132 -
14.4 Driving plate ................................................................ - 132 -
14.5 Clutch/Driven wheel .......................................................... - 134 -
14.6 Disassembly of clutch and driven wheel ........................................... - 136 -
14.7 Assembly ................................................................... - 139 -
14.8 Feet start mechanism .......................................................... - 139 -
- 3 -
Preface
This maintainence manual mainly describes the maintainence essentials of the
Qiangjiang QJ50T-21T.
The Preparation Data include all the operation precautions, please read this
maintainence manual carefully before any operation.
Check & Adjustment mainly describes the essentials of check and adjustment,
vehicle safety and the performance maintenance method of various components.
Check & Adjustment should be implemented from the time of periodic check.
The content after Chapter I mainly describe the assembly, disassembly and
check essentials of motor, complete vehicle and electric fittings.
Every Chapter is accompanied by an exploded view, system diagram, and failure
diagonosis and instructions during the editing.
Notice:
Actual product may differ from the photo or illustration on the manual. The style
or structure of the vehicle shall be subject to other changes without further notices.
KEEWAY Motorcycle Co., Ltd
- 4 -
Preparation Data
General Safety Maintenance Regulations
Specification Sheet Failure Diagonosis
General Safety
Carbon Monoxide (CO)
If the motor has to been started, make sure the working space is well ventilated, the motor can not be run in closed
space.
Caution
The exhaust gas contains toxic gas carbon monoxide (CO), which may render people unconscious or even cause
death.
The motor should be run in the open space, if in closed space, the gas scavenging system shall be used.
Gasoline
The vehicle shall be worked in a well ventilated place, no smoking or naked lights in working place or
gasolince-stored place.
Storage Battery
Storage battery may emit explosive gas, which should be far away from sparkles, naked fire and smoking areas.
The space shall be well ventilated when charging the battery.
Storage battery containes sulphuric acid (electrolyte). It will cause serious burns if it gets on the skin or eys.
Therefore, protective clothing and face mask should be worn in operation.
——Please flush with water immediately if the electrolyte gets on the skin.
——Immediately flush with large amounts of water for at least 15 minutes and seek medical attention
immediately if the electrolyte gets on the eyes.
The electrolyte is tocix. If swallow any of such electrolyte by mistake, immediately drink large amounts of water,
milk and milk of magnesia (a kind of laxative antacid) or vegetable oil and seek medical attention. Keep it out of
reach of children.
Users shall not disconnect the storage battery during the adjustment of complete vehicle, otherwise may cause
internal damage to the components of the whole vehicle.
- 5 -
Maintenance Regulations
During the maintence of the motorcycle, please use the metric instruments whenever possible, improper
instruments may cause damage to the motorcycle.
Before the maintainence operation of disconnecting or opening the protecting plate, please eliminate the pollution
outside the parts or assembly parts to prevent the pollution fall into the motor, bottom plate or brake system.
After disconnecting and before measuring the wear value, please
purge the components and blow through with the air compressor.
The rubber parts may deteriorate because of aging, which is
extremely damaged by solvents or oil. Therefore it should be
checked before reassembly and replaced when necessary.
When loosing the components which have many assembly parts,
the loosing sequence should be from exterior to interior, and the
samll assembly part should be loosed first.
The complex assembly part such as speed gear box shall be
stored in proper sequence for the easy assemble in the future.
Special attention should be paid to the important attachment
postions before disassembly. The non-used components should
be replaced in time before disassembly.
- 6 -
The length of bolt or screw is different in terms of assembly parts
and protective plate. It should be installed in the right position, if
confused, place the bolt into the hole to check whether it fits or
not.
When installing the oil seal, please fill the grease lubricant into
the oil seal groove, and check the oil seal is smooth or not,
otherwise it may damage the oil seal.
When installing the rubber hose (fuel oil, vacuum or coolant), the
end of the rubber hose shall be inserted into the connection
bottom, so that the hose clamp has enough space to grip the
connection. The rubber of plastic dust cover shall be put into the
original design position.
Disassembly of ball bearing: use the instrument to withstand one
or two (inside and outside) bearing race ring. If the strength is
only used on one race ring (no matter inside or outside), it may
cause damage to bearing when disassembling and the bearing has
to be replaced.
- 7 -
The loose cable is the potential electric safety hazard. After
clamping the cable, please check the following one to ensure
the electric safety;
The wire clip is not allowed to bend towards the welding spot
direction;
Please bind the cables at the specified position；
The cable can not be routed on the end or closed angle of the
frame;
The cable can not be routed on the end of bolt or screw;
The cable routing shall be kept away from a heat source or
the place which may clip the cable when moving;
Over tightening or over loosening shall be avoided when the
cable is routed along the cocket handle, and no contacting
with the adjacent components in any steering position;
The cable routing shall be smooth without twisting or
knotting;
Please confirm if there is any damage to the connector
assembly sheath or any excessive expansion of the connector
assembly before the butt joint of the onnector assembly;
If the cable is placed on the closed angle or corner, please use
tape or hose to protect;
Please use the tape to wrap the cable after repairing;
The control wire shall be free from twisting or knotting. Any
damage to the control wire may cause inadequate control;
- 8 -
Motorcycle Identification
1．The motorcycle indentification number is printed on the
frame ① , please see Figure 1-1. Indentification number:
LBB11B05?????????. The ninth number of the vehicle
indentification number is the chek code, the tenth one year code
and the eleventh one assembly factory code. The frame
nameplate is riveted on the left side ② of the frame.
Figure 1-1
2．The engine series number ① is printed on the outer shell
of crankcase, please see Figure 1-2.
Figure 1-2
Important Notices:
1．Please use the pure components manufactured by Qiangjiang. Use the components not complying with the
design specifications of Qiangjiang Company may cause damage to the engine.
2．Use only the metric instruments to do the maintainence operation. The metric bolt, nut and screw are not
interchangeable with the British fastener.
3．When reassembling, new washer, O ring, split pin and locking plate should be replaced.
4．When tightening bolt or nut, unless otherwise specified, bolt with larger diameter or near the inner side should
be tightened first, then along the diagonal line, gradually tighten the bolt to stated torque.
5．Wash the disassembled parts with cleaning solution. Lubricate all the sliding surfaces before assembling.
6．After assembling, please check all the components are assembled and operated in a proper way.
7. Eliminate the pollution and oil before measuring, and add the recommended lubricant onto the oil site when
assembling.
8. If the engine and drive system need to be stored for a long time after disassembling, please spread lubricant
onto the surface of the parts to prevent rusting and dust.
- 9 -
Special Tools
Special tools are the specially designed tools used for special positions in order to assemble or disassemble
certain parts of the motorcycle. Proper special tools are essential in terms of the complete and proper adjustment
and assembling. The special tools can assemble and disassemble parts safely, dependably and quickly, which can
improve working efficiency by saving labor and energy.
1 Tools used for the overhaul of engine
When assembling and disassembling the engine, specially designed tools are needed to properly assemble and
disassemble some parts.
The special tools list to assemble and disassemble the engine parts and the corresponding physical figure,
please see Table 1-1 and 1-2.
Table 1-1
Name
Note
special socket wrench
clutch clamper
flywheel extractor
proof stick
bearing disassembling tool
bearing assembling tool
oil seal assembler/disassembler
dismantling tool handle
piston pin pulling off device
piston ring opening pliers
spark plug socket wrench
measuring the thickness of clutch
cylinder diameter determinator
dial gauge
Used for assembling and disassembling Flywheel Bolt, Figure 1-3
Figure 1-4
Figure 1-5
Figure 1-6
Figure 1-7
Figure 1-8
Figure 1-9
Figure 1-10
Figure 1-11
Figure 1-12
Figure 1-13
Figure 1-14
Figure 1-15
Measuring the inside diameter of piston pin hole，Figure 1-16
Continuation Table 1-2
Figure 1-3 Figure 1-4
- 10 -
Figure 1-5 Figure 1-6
Figure 1-7 Figure 1-8
Figure 1-9 Figure 1-10
① Handle
Figure 1-11 Figure 1-12
- 11 -
①Opening pliers ②Piston
Figure 1-13 Figure 1-14
Figure 1-15 Figure 1-16
2．Tools used for the overhaul of chassis
The special tools list to assemble and disassemble the chassis parts and the corresponding physical figure,
please see Table 1-11 and 1-18.
Table 1-17
Name
Note
torque wrench
inner hexagonal wrench
socket wrench
micrometer
magnetic frame, V-block
dial gauge
vernier caliper
spring retaining ring pliers
knocker screwdriver
front fork oil seal assembling tool
front fork seal driver
steering nut wrench
Figure 1-19
Figure 1-20
Figure 1-21
Figure 1-22
Figure 1-23
Figure 1-24
Figure 1-25
Figure 1-26
Figure 1-27
Figure 1-28
Figure 1-29
Figure 1-30
（1）Universal tool for the overhaul of chassis
Continuation Table 1-18
- 12 -
Figure 1-19 Figure 1-20
Figure 1-21 Figure 1-22
Figure 1-23 Figure 1-24
Figure 1-25 Figure 1-26
Figure 1-27 Figure 1-28
（2）Special tool for the overhaul of chassis: front fork seal driver.
- 13 -
Figure 1-29
（3）steering nut wrench.
Figure 1-30
3．Tools used for electrical parts
The special tools list to test the electrical parts and the corresponding physical figure, please see Table 1-31
and 1-32.
Table 1-31
Name
Note
avometer
ignition tester
Figure 1-33
Figure 1-34
Continuation Table 1-32
Figure 1-33
Figure 1-34
- 14 -
Specification Table (QJ50T-21T)
Model
QJ50T-21T
Engine
Type of engine
QJ1E40QMB-4
Full length mm
1860
Type of fuel
lead-free gasoline
（93/95）
Full width mm
680
Number of
cylinders
1
Full height mm
1198
Inside
diameter*stroke
49.2×39.2
Wheelbase mm
1290
Total
displacement
49.3cc
Weight of vehicle
kg
（Curb weight）
front axle
40
Initiate mode
Electric/foot initiate
Rear axle
59
Cooling system
Wind cooling
Total
99
Lubrication type
Separating lubrication
Wheel
specification
Front
wheel tyre
120/70-12
Front
wheel rim
3.50×12
Air cleaner
3XG
Rear
wheel tyre
130/70-12
Rear
wheel rim
3.50×12
Fuel tank
capacity
5.6L
Driving mechanism
Type of
clutch
Dry centrifugal type
Carburetor model
PZ19JB
Variable
speed
mechanism
infinite variable speed
Performance
Idling speed -rpm
1800±100rpm/min
Driving type
belt transmission
Maximum torque
4.0N.m/6500rpm
Electrical installation
Storage
battery
capacity
/Type
12V-3AH/dry-charged
Maximum
horsepower
2.7kW/6500 rpm
Magneto
capacity
89.6W/5000rpm
Compression
ratio
6.9：1
Spark plug
BR8HSA
Maximum speed
45km/h
Spark plug
gap
0.6-0.7mm
Brake
apparatus
Front brake disc
Diameter（mm）
φ190mm
Ignition type
CDI
Rear brake drum
inside diameter
（mm）
φ175mm
- 15 -
QJ50T-21T
- 16 -
No
Yes
No
Yes
Yes
No Y No
Failure Diagnosis
Failure diagnosis procedure when the engine fails to start or start difficultly
Engine fails to start or start difficultly
Check the ignition system
Remove the spark plug, check the electrodes of spark plug are carbon connected
Do the spark plug spark over test
To clean out carbon
Faint or no spark between electrodes
Strong blue or bluish violet spark from the electrodes
Screw off the spark plug cap, do high-voltage wire spark over test
Use ignition timing light to test whether engine ignition is timing
Strong blue spark
Faint or no spark
Check if the spark plug, spark plug cap fails
Check the
supply of
ignition
power
Check if
there is short
circuit or
broken
Check if there
is short circuit
or broken
circuit of the
internal system
of ignition
Check if the
CDI ignition
apparatus
fails
Use the cylinder
pressure gauge to test
the cylinder
compression pressure
Check if there
is fuel in the
fuel tank
Cylinder
compression
pressure
normal
Cylinder
compression
pressure
insufficient
To
fill
the
fuel
No contact magneto ignition system
1. Check if there is short
circuit or broken circuit of
ignition power winding
2. Check if there is short
circuit or broken circuit of
trigger winding
1. Check if the CDI ignition
apparatus fails
2. Check if the magneto
flywheel and trigger
winding loosen
Loosen carburetor fuel
draining screw, check if
there is fuel draining
from the carburetor
overflow pipe
- 17 -
Yes
No
Spark plug electrode is moist
Spark plug electrode is dry
Check if there is oil leaking from
carburetor
Instill small amount of fuel into the cylinder to
have an experimental starting
1. Check if there is gap
between the carburetor float
needle valve and valve seat
because of other materials
2. Check if the conical
surface of the carburetor
float needle valve is worn
into step shape
3. Check if the carburetor
float breaks
4. Check if the carburetor
float is too low
Check if the air
cleaner blocks
The engine stops after
running a very short time
Work continuously after
starting
The carburetor inside
blocks or the float is
too high
Carburetor starting
device (starting richer
system) fails
1. Check if there is gas leaking
in external connections of the
engine
2. Check if the piston ring sticks
in ring groove or insufficient
elasticity
3. Check the wearability of
piston ring and cylinder
1. Check if the venthole of
fuel tank cover blocks
2. Check if the fuel filter and
fuel cock block
3. Check if the fuel cock
works well
4. Check if the carburetor inlet
port blocks
5. Check if the carburetor
floater is too high
Remove the
spark plug to
test
- 18 -
Yes
No
Yes
No
Yes
No
No
Yes
Yes
No
The engine overheat failure diagonosis procedure
Engine overheat
Check if the operation method is proper
1. Check if the fuel No. is too low
or the fuel is out of date
2. Check if the engine runs at high
speed or overload for a long time
Check the cooling system
Air cooled engine
Check if the cooling fins are stained with silt or too much oil
Wash
Check if the cooling fans and
wind scoop break (compulsive
air cooled engine)
Check and
eliminate
Use ignition timing light to test
whether engine ignition is timing
1. Check if the CDI
ignition apparatus
fails
2. Check if the
magneto flywheel
and trigger winding
loosen
Check if the clutch slips
Clutch slips
To treat the clutch
slip failure
accordingly
- 19 -
Remove the spark plug, watch the color of spark
plug insulator cluster and determine the mixture ratio
of the combustible gas mixture in accordance with
the different abnormal appearances
Spark plug insulator cluster is white, the
exhaust muffler smokes or blast when the
engine is running at medium and low speed, the
accelerating ability is bad, idle speed is unstable
and tends to stop easily, relatively normal when
running at high speed.
spark plug insulator cluster is brown
Spark plug insulator cluster is
white, the engine is intermittent
when accelerating, carburetor
backfires and the engine power is
insufficient etc
combustible gas mixture is too strong
1. Check if the air cleaner blocks
2. Check if the carburetor starting
device (starting richer system)
works well
3. Check if the carburetor float is
too low
the mixture ratio of the
combustible gas mixture is proper
Check if the vent of
cylinder and exhaust
muffler block because
of too much carbon
Check lubricating
system
combustible gas mixture is
too weak
Two-stroke engine
lubricating system
1. Check if the fuel
cock works well
2. Check if the
carburetor float is too
high
3. Check if the orifices
and pore canals on the
1. Check if the fuel in the
crankcase is insufficient
2. Check if the viscosity of fuel
in the crankcase is too low or the
fuel is too dirty
3. Check if the fuel filter blocks
4. Check if the fuel pump works
well
5. Check if the lubricating oil
path blocks
- 20 -
Yes
No
Underpowered engine failure diagnosis procedure
Engine underpowered
Prop up the main jiffy stand to make the wheels lift-off, revolve wheel by hand
Wheel spins smoothly
Wheel spins stiffly
Check the tyre pressure
1. Check if the brake drags
2. Check if the wheel bearing is
overused or damaged
3. Check if the loading of hub’s
central spacer is neglected or
shorter
Air pressure too low
Air pressure normal
Check if the tire valve core
leaks and if the tire breaks
Remove the spark plug and block the spark
plug threaded hole with hand, then press the
starting button or step on the starting bar
Fingers can feel a strong gas blowing
outside, with the sound of pow at the
same time
Fingers can not feel a strong gas blowing outside
Cylinder compression pressure normal
Cylinder compression pressure insufficient
1. Check if there is gas
leaking in external
connections of the engine
2. Check if the piston ring
sticks in ring groove or
insufficient elasticity
3. Check the wearability of
piston ring and cylinder
Start the engine and step on the gas
slowly to watch the change of
engine’s rotating speed
The rotating speed of the engine accelerates
as the driver step on the gas
The rotating speed of the engine does
not accelerate as the driver step on the
1. Check if the clutch skids
2. Check if the transmission belt is over worn
3. Check if the centrifugal roller of the
driving pulley is over worn
4. Check if the conical surfaces of driving
wheel and moving friction wheel are over
worn or worn into groove
5. Check if the conical surfaces of following
pulley and moving following pulley are
over worn or worn into groove
6. Check if the roller track on the internal
side of moving friction wheel are over worn
or extruded into a drop pit
1. Check if the supply of fuel feeding
system is smooth
2. Check if the carburetor, air cleaner and
exhaust muffler block
3. Check if the vacuum diaphragm of
carburetor plunger valve cracks or
breaks
4. Check if carburetor float height is
improper
1. Check if the CDI
ignition apparatus fails
2. Check if the
magneto flywheel and
trigger winding loosen
Use ignition timing light to test
whether engine ignition is timing
- 21 -
Yes
No
Yes
No
No
Yes
Yes
No
Yes
No
Failure diagonosis procedure of unstable engine idle speed
Bad idle speed of engine
Engine’s idle speed too high
Engine has no idle speed
Engine’s idle speed unstable
Check the cylinder compression pressure
Pull the air throttle of carburetor by
hand and check if it is closed
completely
Use ignition timing light to test
whether engine ignition is timing
cylinder compression
pressure insufficient
cylinder compression
pressure normal
1. Check if there is gas
leaking in external
connections of the engine
2. Check if the piston
ring sticks in ring groove
or insufficient elasticity
3. Check the wearability
of piston ring and
cylinder
Readjust the idle speed
of carburetor
Check if
the idling
jet is too
large
Check if the
wire rope of
accelerator
control cable is
flexible in
cable cover and
if the air
throttle spring
1. Check if the CDI
ignition apparatus fails
2. Check if the magneto
flywheel and trigger
winding loosen
Engine has idle
speed after
adjustment
Engine still has
no idle speed
after adjustment
The carburetor air
adjusting screw
or air throttle
adjusting screw is
adjusted
Check if the idling jet of
carburetor, idling oil
channel and air flue
block
Wash and clear out
Check if carburetor float is too high
Adjust the carburetor
float height to standard
value
1. Check if there is crackle in the carburetor
insulator
2. Check if the retaining nut of carburetor
loosens
3. Check if the negative pressure pipe of fuel
cock breaks
4. Check if the leaf valve leaks
Adjust the gap of
electrodes
Check the mixture
ratio of the
combustible gas
mixture
Check if
the gap
between
spark plug
electrodes
is too
small
- 22 -
Yes
No
Yes
No
Yes
No
Yes
No
Failure diagnosis procedure of engine’s excessive fuel consumption
Excessive fuel consumption of engine
Check if the operation method is right
Prop up the main jiffy stand and revolve wheel by hand
1. Check if the motorcycle is run
overloaded, or run not at
economical speed or run at low
gear
2. Check if the gasoline number is
right
Wheels revolve difficultly
Wheels revolve smoothly
1. Check if the brake
drags
2. Check if the wheel
bearing is overused
3. Check if the loading
of hub’s central spacer
is neglected or shorter
Check the tire pressure
Tire pressure is too low
Tire pressure is normal
To charge as required
Check there is fuel leaking in
the fuel tank, fuel cock, fuel
pipe and carburetor
To exclude in accordance with the actual situation
Check the mixture ratio of the
combustible gas mixture
The mixture ratio of the combustible
gas mixture is normal
Combustible gas mixture is too strong
Combustible gas mixture is too weak
Check if the engine idle speed is too high
1. Check if the air cleaner
blocks
2. Check if the carburetor
float is too low
3. Check if the main jet of
carburetor is too large
1. Check if the inside of
carburetor blocks
2. Check if the carburetor
float is too high
Check and adjust the
carburetor
Use ignition timing
light to test whether
engine ignition is
timing
Check if the transmission
belt of clutch slips
Check ignition system
- 23 -
Yes
No
Yes
No
Yes
No
No
Yes
Yes
No
Failure diagnosis procedure when the exhaust muffler of two-stroke engine gives off strong blue and white
smoke
Failure diagnosis procedure when the gear shift is difficult to shift
The exhaust muffler of two-stroke engine gives off
strong blue and white smoke
Check if the engine oil level in the crankcase exceeds the upper label
If the engine oil in the crankcase is
overfilled, please drain out the excess
oil and make sure the oil level does
not exceed the upper label
1. Check if the cylinder, piston and piston
ring are over-worn
2. Check if the elasticity of piston ring is
insufficient or sticks in ring groove
3. Check if the opening positions of piston
ring are staggered
The gear shift is difficult to shift
Start the engine and check if the idle speed of the engine is too high
Readjust
Check if the gear-shifting operation is coordinating
Check if the clutch is separated completely
Improve the operation method
Check if the gear-shifting axis is deformed, and if the
gear-shifting arm is deformed or over-worn
1. Check if the free stroke of clutch
lever is within 10mm ~ 20mm
2. Check if the spring force of clutch
is even
3. Check if the driving and driven hub
alveolus are worn to indention
4. Check if the clutch driven plate is
deformed
5. Check if the parts of clutch control
mechanism are over-worn
Replace
1. Check if the gear-shifting camshaft and
cam groove are over-worn or damaged
2. Check if the shift fork hole is over-worn
3. Check if the shift fork is deformed
4. Check if the declutch shift shaft is
deformed or over-worn
Start the engine and make it run at high
speed, remove the engine oil scale to check if
the engine oil filling port smokes
- 24 -
No
Yes
No
Yes
No
Yes
Yes
No
Yes
No
No
Yes
Failure diagnosis procedure when there is trip dog of the gear shift
Failure diagnosis procedure when the clutch slips
Clutch slips
Automatic centrifugal dry block clutch slips
Check if the block friction
dis of the clutch is
over-worn
Replace the whole clutch block set
Eliminate the oil
Check if the contact area
between the clutch block
friction dis and clutch
friction plate is less than
70％
Check if the contact area
between the clutch friction
plate and block friction dis are
Repair or replace
clutch block
Check if the block friction dis of the clutch is stained with oil
Trip dog of the gear shift
Check if the positioned wheel spring breaks or the spring force is insufficient
Replace
Disassemble the crankcase, check if the gear wheel engaging depths of
various gears are up to requirement
Engaging depth of gear wheel is enough
Engaging depth of gear wheel is insufficient
Check if the cam claw engaging end of the meshing gear end
face is worn to conical or round shape, and if the
corresponding gear face groove is worn to pipe socket
Check if the shift fork is
over-worn or deformed
Replace the gear
Check if the spline teeth of
main shaft and counter shaft
and the spline groove of
Replace the shift
fork
1. Check if the shift fork hole and declutch
shift shaft are over-worn
2. Check if the fitting clearance between
the shift fork pin and the gear-shifting gear
shaft and the cam groove are too large
- 25 -
No
Yes
Yes
No
No
Yes
Failure diagnosis procedure when the hydraulic disc brake fails
Failure diagnosis procedure when the drum brake fails
hydraulic disc brake fails
Check the brake fluid level in the brake primary pump liquid reserve tank
The brake fluid level below the lower limit of liquid
reserve tank
The brake fluid level above the lower limit of
liquid reserve tank
Fill the brake fluid to the
upper limit of liquid reserve
tank, at the same time
check if there is oil leaking
in the brake caliper, brake
hose and hose joints
Check if there is ―sponge‖
feels when operating the
brake lever
There is residual air
in the fuel line of
brake system
Check if the brake friction disc is
worn to limit mark and if the brake
plate is over-worn
Replace the brake
friction disc and
the brake plate
Drum brake fails
Check if the free stroke of brake lever is within 10mm
~ 20mm or check if the free stroke of brake pedal is
within 20mm ~ 30mm
Readjust
Separate the steel ropes of brake rocker arm and brake control cable, then
pull the brake rocker arm by hand to check
Brake rocker arm
revolves smoothly, but
you feel resistance
when holding the
brake handle
Brake rocker
arm revolves
difficultly
The arrow on the indicating
plate of brake cam aligns with
or exceeds the ―▽‖mark on
the brake wheel hub cap
The arrow on the indicating plate
of brake cam does not align with
the ―▽‖mark on the brake wheel
The wire ropes of
brake control
cable can not be
pulled smoothly
in the cover
1. Check if the crown face of the brake
cam is over-worn
2. Check if the brake block friction disc
is over-worn
3. Check if the brake wheel hub inside is
over-worn
1. Check if the surface of brake primary pump piston and oil
cylinder is over-worn
2. Check if the leather cup of brake primary pump piston cracks or
is damaged or ageing
3. Check if the seal ring of brake caliper cracks or is damaged or
ageing
4. Check if the surface of brake caliper and oil cylinder is
The movable
parts of the
brake cam are
rusted or stuck
in foreign
materials
1. Check if the surface of brake
block friction disc is stained with
oil
2. Check if the contact area
between the brake block friction
dis and brake hub is less than 70％
- 26 -
Yes
No
Failure diagnosis procedure when the storage battery can not be charged
The storage battery can not be charged
The resistance value is smaller than
standard value
Short circuit of
charge coil
The resistance value is infinite
The resistance value is equal to
standard value
Short circuit of charge
coil or its output wire
Place the multimeter in the 0V~20V DC
voltage, measure the voltage of the insert
connector to the conductor terminal of storage
battery (generally red wire or red/white wire)
and negative pole
The circuit from the magnetor to
commutator or commutation
regulator is in poor contact or
broken
No voltage indicates
Voltage indicates
Circuit from the
insert connector
to storage battery
Use the ohmmeter to test the
commutator or test if the
commutation regulator fails
Disconnect the insert connector of magnetor wire
bundle and the complete vehicle cable, use the
ohmmeter to measure the resistance between the
output wire ends of charge oil, and check if it
meets the standard value
Connect the insert connector between the magnetor
wire bundle and the complete vehicle cable, disconnect
the insert connector between the commutator or
commutation regulator and the complete vehicle cable
Use the ohmmeter to measure that if the resistance
between the output wire ends of charge oil in the insert
connector is equal to the resistance of the charge coil
itself
- 27 -
Yes
No
Yes
No
Failure diagnosis procedure when the storage battery is undercharged
Storage battery is undercharged
Check if the brake lamp is on
Adjust or replace the brake
lamp switch
Leakage current is less than the specified value
Leakage current is greater than the
specified value (it is generally required
that the leadkage current is no greater
than 1mA)
Check if the charging coil of magnetor is
shortcircuited
The wire from the commutator
or the commutation regulator or
the storage battery to the ignition
switch is shortcircuited
Replace the
charging coil
1. Check if the electrolyte in the storage battery
is insufficient
2. Check if electrolyte concentration in the
storage battery is too low
3. Check if the polar plate in the storage battery
is sulfurized or shortcircuited
Put the ignition switch in ―OFF‖ position, remove the negative pole wire from the
storage battery, connect the ammeter negative pen to the negative ternminal of storage
battery and positive pen to the negative pole wire to check the leakage current
- 28 -
Riding motorcycle
Seat-type Motorcycle
Yes
No
Yes
No
Failure diagnosis procedure when the start motor is unable to rotate
The electric horn does not sound
or the sound is weak, and the
light of turn signal is pale
The sound of the electric horn is
loud and the light of turn signal is
bright
The electricity in the storage
battery is insufficient or the wire
terminal connecting the storage
battery is in poor contact
Hold the brake handle (seat-type motorcycle)
tightly, or put the gear shift in neutral gear or hold
clutch handle tightly, press the start button
Start motor is unable to rotate
Turn on the ignition switch, press the horn button or toggle the turn signal switch
Press the start button, you can not hear the connection sound of
the start relay
Press the start button, you can hear the
connection sound of the start relay
Remove the insert connector of the start relay from the
complete vehicle cable, then use two wires to connect the
positive terminal and negative terminal of the storage battery
and the two leading wires of start relay coil
Use the screwdriver or heavy gage wire
to short-circuit the storage battery
terminal on the start relay with the start
motor terminal
The start relay can
rotate normally after
connecting
The start motor can
rotate normally after
shorting
The start motor can not
rotate after connecting, and
the connection sound of
start relay can not be heard
either
The start motor does
not rotate after
shorting
The start relay coil
is broken or
short-circuited
Check if the line of electric start
control system
The start relay
contact is burnt or
damaged
Disassemble the start motor and do
the following inspections:
1. Check if the carbon brush is
over-worn
2. Check if the carbon brush spring
breaks or the spring force is
insufficient
3. Check if the surface of armature
commutator is over-worn
4. Check if the armature coil is
broken or short-circuited
1. Check if the starting
button contact is in poor
contact
2. Check if the
commutating diode is
damaged
3. Check if the neutral gear
switch works well
4. Check if the line of
electric start control system
is broken or short-circuited
Check if the starting
button contact is in
poor contact
Hold the brake handle tightly and check if the brake lamp
will light up
The inside contact of brake
lamp switch is in poor
contact or its wires are
broken
Repair or replace
the starting button
Check if the line of electric
start control system is
broken or short-circuited
- 29 -
No
Yes
Yes
No
Failure diagnosis procedure when the start motor is weak in rotating
Start motor is weak in rotating
Turn on the ignition switch, press the horn button or toggle the turn signal switch
The electric horn does not sound
or the sound is weak, and the
light of turn signal is pale
The sound of the electric horn is
loud and the light of turn signal
is bright
The electricity in the storage
battery is insufficient or the wire
terminal connecting the storage
battery is in poor contact
Check if the wire terminal between
the relay and the start motor is in
poor contact
Remove the start motor connecting wire and storage battery
connecting wire from the start relay, press the start button,
when the start relay makes the connection sound, use the
ohmmeter to measure the resistance between the storage
battery wiring terminalon the start relay and the start motor
wiring terminal, and check if the resistance is smooth
Check and exclude
Disassemble the start motor and do the
following inspections:
1. Check if the carbon brush is over-worn
2. Check if the carbon brush spring breaks or
the spring force is insufficient
3. Check if the surface of armature commutator
is stained with dirt or is burnt or damaged
4. Check if the armature commutator is
over-worn
The start relay contact is
burnt or damaged
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